- Melt 3 tablespoons butter in a large stock pot.
- Add leeks and celery and sauté over medium heat until soft, about 10 minutes.
- Add in potatoes, ale, stock, salt and pepper, and bring to a boil.
- Lower heat and cover and continue to simmer until potatoes are tender.
- Melt remaining butter in a small saucepan, gradually add flour and whisk until smooth.
- Cook about 3 minutes over med/low heat while stirring constantly, slowly pour in the milk, and whisk until it begins to thicken.
- Add cheese and stir until melted.
- Pour cheese mixture in to potato mixture and cook another 10 minutes over very low heat.
- Ladle into soup bowls and garnish with fresh chopped parsley, bacon crumbles and croutons if desired.